Hubbert was “a scientist who cared only for the objective truth”. This statement is not intended as a slight against so-called ‘black hat’ scientists, who were motivated by ill intentions. I intended this more an indication that Hubbert was charting his own course, guided by the best data that he found. Hubbert was doing this with certain insights that others lacked (which was not the fault of the other scientists).
Doel (2006) says Hubbert wanted the freedom to pursue research and “draw whatever conclusions the facts led to”. Hubbert (1989h) said whilst working for the USGS “my first loyalty was to the American taxpayer”.

‘Half-tonne rails’ used by Union Pacific Nebraska: Rails of the 1920s-era weighed 90 lbs/yd (source: personal correspondence with Piers Connor from railway-technical.com). Piers also stated it is likely that the Union Pacific rails were 33ft long during this time. So each rail would have been 449.1kg heavy (“Wolfram Alpha”, n.d.). i.e. roughly half a tonne.

Pennsylvania was on the ‘decline side’ of its oil production curve. Refers to the fact that Pennsylvania had two peaks (1891 and 1937) and then a decline in production by the time of Hubbert’s 1956 study. From Hamilton (2010) and “Pennsylvania” (2000).

King and Miriam Hubbert getting mobbed by journalists at their hotel: Hubbert (1989g). This incident really happened, but probably didn’t occur in the dramatic ‘media scrum’ way that I depicted!

“Hubbert’s views about the bell-shaped nature of oil production were known prior to the conference.” Hubbert publicly challenged the estimates of petroleum geologist A. I. Levorsen at a United Nations meeting in 1949: Hubbert (1989f). Because of this, Hubbert’s assertions appeared on the front page of the New York Times the following day Clark (1983).

Chose the best reserve estimates “on geological merit”. In 1956 he plotted two scenarios for the ‘high’ and ‘low’ estimates of 150 and 200 billion barrels of oil: Hubbert (1989g), Clark (1983). In 1962 Hubbert used a single ‘best estimate’ of 170 bbl: “Biography: Hubbert, Marion King” (2008, p. 398), Clark (1983).

“The American roller coaster had started being built in 1859”. Oil was first drilled commercially in the United States in the state of Pennsylvania in 1859: Heinberg (2003, p. 57) and Hubbert (1976, p. 115).

Some oil industry executives and U.S. Geological Survey staff did not accept Hubbert’s analysis: “Biography: Hubbert, Marion King” (2008, p. 398) and Hubbert (1989g). Hubbert’s 1989 interview with Doel goes into extensive detail about the aftermath and rival forecasts. Hubbert describes the oil industry as splitting into two camps. One group accepted the figures and realised they couldn’t change or disguise them. The other camp refused to accept the statistics and dodged reality by postulating inflated oil estimate figures. Vincent McKelvey from USGS quickly backed the inflated Zapp estimates once released (see below).

Oil depletion being “a vague concept for grandchildren to worry about” Hubbert (1989g) claimed that up until his API presentation the industry’s ‘stock answer’ was that the U.S. had all the oil it needed for the foreseeable future. His 1956 paper forced the industry to re-evaluate this supposition.

Rival forecasts were ‘written by economists’: “Biography: Hubbert, Marion King” (2008, p. 398) and Hubbert (1989g). Examples cited of alternative forecasters: Morgan Davis & Richard J. Gonzalez from Humble Oil and Bruce Netschert. Hubbert also noted that non-profit organisation Resources for the Future is primarily staffed by economists. (Note that A.D. Zapp, whose paper is shown on this page, was a geologist, not an economist.)

“Speculative assumptions about future oil discoveries in areas where oil was unlikely to be found”: Hubbert (1989g) noted that Bruce Netschert (1958) assumed that oil could be drilled from a depth of 65,000 feet when the current proven drilling depth was less than 25,000 feet. Zapp’s 1961 ‘volumetric yield’ technique extrapolated the oil production yields of well-explored, oil-rich parts of the U.S. to other unexplored parts of the U.S. (which would later be shown to oil-poor by comparison).

“Hubbert knew that history, not PR, would truly test his theory”: Hubbert (1989i) described his approach as like that of Galileo. In other words: let the experiment itself show the results.

U.S. contiguous oil production peaked in 1971: “Biography: Hubbert, Marion King” (2008, p. 398). ‘Contiguous U.S.A.’ is a term referring to the ‘lower 48 states’ of America. Alaska and Hawaii did not become U.S. states until 1959, after Hubbert published his 1956 API paper.

Globally, fewer and fewer barrels discovered every year since the mid-1960s: Heinberg (2003, p. 38), Hallett and Wright (2011, p. 122), Gilding (2011, p. 124) and Heinberg (2011, p. 111) state that discoveries peaked around 1963. Hubbert (1989g) stated that the peak of discoveries was “a clue of how close you were to the peak of production”.

Energy alternatives are unlikely to match “oil in its heyday”: Heinberg (2004, pp. 19–20), Heinberg (2011, pp. 159–61), Hallett and Wright (2011, p. 176). In other words, we will be moving to substitute fuels which are less compact and less energy-dense than oil. I use the term “heyday” to refer to the boom-era of the oil industry, when drilling was relatively cheap and easy. We may choose to turn to ‘unconventional oil’ sources, but they are relatively expensive and energy-intensive to refine.

From the peak of fossil fuels, we must transition to “a civilisation fuelled by a lower level of energy”: Hubbert (1976, pp. 124–6) saw that we needed cultural adjustment post-Peak Oil.

Hubbert’s chart extended 5,000 years in both directions was published in Hubbert (1976, p. 124). In that paper, Hubbert described its appearance as “a Washington Monument-like spike. Representing one of the most disturbing influences ever experienced by the human species in its entire biological existence”.

“It is likely that the track today is about as high as it will ever be”: Heinberg (2007, pp. 3–4), Heinberg (2009, p. abstract). Hallett and Wright (2011, pp. 122, 124, 244) point out that, without us noticing, many of our record-breaking achievements like lunar missions, land-speed records, etc are decades behind us.

We won’t be certain we’ve passed the peak until we see it over our shoulder: Hallett and Wright (2011, p. 247).

We can’t change the past, we can only change the future: Gilding (2011, p. 3).

Assumption 1: the ‘ancient plant matter’ in question is 50% carbon.Assumption 2: The contemporary ‘coal’ in question is medium rank bituminous coal. Composition: 86% carbon.Assumption 3: 13% of the original plant carbon remains after being geologically converted from vegetation into coal. [Taken from Dukes (2003, p. 34): “the average of these products is 13%”].
This is the ‘preservation factor’ (PF) of fossil fuel-precursor into the final fossil fuel.Working:

Start with 1 tonne of bituminous coal
Bituminous coal is 86% carbon

1 x 0.86 = 0.86 tonne of carbon.
This carbon is only 13% of the original plants’ carbon.

0.86 ÷ 0.13 = 6.62 tonnes (this is the mass of the original carbon precursor, before reduction during the coalification process).
Plant matter is 50% carbon so we double this to get mass of original plant matter

6.62 x 2 = 13.2 tonnes original plant matter.

This approximate 1:13 ratio allows us to make the following statement on page 18:“Each 11 kg shovelful of coal held the condensed energy of about 150 kg worth of fossilised plant matter.”

Oil calculations:

Assumption 1: the ‘ancient plant matter’ in question is 50% carbon.Assumption 2: The contemporary ‘oil’ in question is 85% carbon.Assumption 3: 1.4% of the original plant carbon remains after being geologically converted from vegetation into crude oil. This is adjusted figure from Dukes, (2003, p. 35), chosen in consultation with Dukes via email correspondence. Instead of using the “2%” figure quoted in his paper, I use 1.4%
This incorporates both the ‘preservation factor’ (PF) of fossil fuel-precursor into the final fossil fuel, and the ‘genetic potential’ of the types of kerogen generated in each settingWorking:

Start with 1 tonne of contemporary crude oil
Crude oil is 85% carbon

1 x 0.85 = 0.85 tonne of carbon.
This carbon is only 1.4% of the original plants’ carbon.

0.85 ÷ 0.014 = 60.7 tonnes (this is the mass of the original carbon precursor, before reduction during the oil maturation process).
Plant matter is 50% carbon so we double this to get mass of original plant matter

60.7 x 2 = 121 tonnes original plant matter. Therefore we can say:

“Each tonne of crude oil held the condensed energy of about 120 tonnes of fossilised plant matter.”

Note that I refer to dry weights with my coal and oil conversion calculations. e.g. the weight of the ancient vegetation matter, excluding the water in the living tree’s issue.

If I had chosen to use wet weights, the conversion factors would have been larger: roughly 2x higher for coal, and 4x higher for oil.